In the past decades, large epidemiological studies of depressive disorders have been conducted worldwide and found that the prevalence of depressive disorders in the general population is 3-10%; among patients with physical illnesses, the proportion of those who also suffer from depression is as high as 20-60% (e.g., cancer patients). Domestic data show that 16 out of every 1000 Chinese suffer from depression, and that it is higher in women than in men, and in rural than in urban areas. However, only a small percentage of patients automatically seek medical help, and the number of patients with depression seen in the clinic is only the “tip of the iceberg”.